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Author Topic: Forest pack pro Edge mode assistance  (Read 734 times)

cgeye

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Forest pack pro Edge mode assistance
« on: March 18, 2016, 01:26:44 PM »
Hi All,

i work in a studio that uses forest pro. We use forest pack to grass lawns but with edge mode we have noticed a brown ghosting effect.

 I believe this is where a clump is being excluded from the render but still leaving the "brown shadow ghost" of its former self :P

i created a test scene and have attached a quick render. We did find that adjusting the secondary ray bias and max transparency levels had some sort of effect, but because we use lots of proxy plants else where in the scene that use transparency it screws them up.

any help would be greatly appreciated.

thanks,

Rob

Michal Karmazín

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Re: Forest pack pro Edge mode assistance
« Reply #1 on: March 18, 2016, 03:16:37 PM »
Hi,

Well, to treat this kind of artefacts caused by many overlapping objects, when V-Ray exceed its default transparency limit, we usually recommend to increase Global switches - Max transp. levels & sometimes might be necessary to modify Secondary rays bias too / use lower density values by increasing Distribution Map - Density X/Y Size.

As you're using proxies in your scene let me add, that as mentioned in our on-line reference guide:

"Please be aware that Edge Mode is not compatible with V-Ray proxies. If you wish to reduce file sizes and use Edge Mode it is recommended to use XRef objects instead."


Actually, it's always possible to use the work-flow explained in the "Grass Edges" tutorial (mixing small / large clumps).

Hope that helps.

Best regards,

cgeye

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Re: Forest pack pro Edge mode assistance
« Reply #2 on: March 20, 2016, 03:12:12 PM »
Hi,

Thanks for replying. I was under the assumption that when It referenced the use of proxies it was talking about them being used at the scatter object in forest pack with which the edge mode doesn't work (in the same way a slice won't hide a proxy) not the fact that you can't use proxies elsewhere in the scene?

Regarding the old edge workaround, we didn't find that this was a suitable way to fix the grass as you could visible see the density change around the edges and with the amount of projects we had to do this on we didn't find it a suitable solution. in the same way that xreffing all the plants isn't viable for our work flow.

Adjusting the global switches doesn't work for us as previously mentioned becuase of the transparency issue but will give the density idea a go on Monday, although I am concerned that his will leave visible patches with no grass on which would be a shame, not so bad for a still photoshop job, but we do animations which would require full cover upon render.

cgeye

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Re: Forest pack pro Edge mode assistance
« Reply #3 on: March 21, 2016, 06:21:33 PM »
So i had i ago, changing the distribution. There really shouldn't be an issue with eh transparency on this file as its so small.
im still getting the issue with the brown ghosting.

any suggestions other than what has been previously discussed?
its a real shame the edge mode doesnt work if other objects in the scene use transparency.

Michal Karmazín

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Re: Forest pack pro Edge mode assistance
« Reply #4 on: March 22, 2016, 09:38:00 AM »
Hi,

Sorry to hear you're still getting those render artefacts.
Quote
"I was under the assumption that when It referenced the use of proxies it was talking about them being used at the scatter object in forest pack with which the edge mode doesn't work (in the same way a slice won't hide a proxy) not the fact that you can't use proxies elsewhere in the scene?"
That's correct (proxy objects can be used in the scene without any problems), I've mentioned the V-Ray proxy limitation just for cases you would use those as items in that Forest object. My apologies for misunderstanding.
Quote
"... if other objects in the scene use transparency."
Would you please describe more in detail how raising the Max transp. limit is affecting those? Did you try to change the Transp. cutoff value? Thanks a lot for all your feedback.

Best regards,

cgeye

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Re: Forest pack pro Edge mode assistance
« Reply #5 on: March 22, 2016, 10:55:36 AM »
when the max transparency levels was set to 75 and the secondary ray bias was set to 50 certain plants became see through, i could still see them but like the pocatiy was turned to about 30%

however,I did a quick test on my small test scene.

i graduated the secondary ray bias in a series of quick renders from 0 (default) up to 60. At 60 the brown ghosts disappeared. i need to test this on my animation though to see if it affects objects with transparency if the numbers are great.

Its an animation of a new housing development (see attached render) so you can imagine there are quite a few proxy plants, about a third are newer xfrog and evermotion plants which rely heavily on transparency for the leaves rather than mesh.

i will check back in with you when i find a few minutes to send a render.

thanks